History of radio astronomy, Steve Torchinsky Goutelas, 4 June 2007 1
History of Radioastronomyfrom 1800 to 2007
(a personal selection)Steve Torchinsky
Observatoire de Paris
History of radio astronomy, Steve Torchinsky Goutelas, 4 June 2007 2
Herschel discoversinvisible radiation
• 1800• For the first time, it
is understood that light has components that are invisible to the human eye
History of radio astronomy, Steve Torchinsky Goutelas, 4 June 2007 3
Hertzian waves
• 1889• First transmission and detection of
radiowaves• “no practical purpose”
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Attempts to Detect the Sun
• 1900 – 1905 non detections• Oliver Lodge
– Not enough sensitivity– Solar minimum
• Nordmann– 175m long wire– galvonometre
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Karl Jansky
• 1932 (published in 1935)• λ 15m• Detected galactic centre
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Radio static from the Sun
• 1936– Solar maximum– Static on radio receivers– No one realised they had detected the Sun!
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Detection of the Sun• 1942
– J.S. Hey in England– λ ~ 1m– correlation with sunspots– not published until 1946 (after the war)
• 1944– Grote Reber detects the Sun and publishes the result
• 1945– Sourthworth in USA– λ ~ O(1) cm– thermal emission from the Sun
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Grote ReberThe Father of Radio Astronomy
• For ~10 years no one followed up Jansky’s discovery
• 1944– λ 2m, 310ft reflector (huge!)– Several maxima including
Cygnus– Continuum emission along
galactic plane– the first radio map of the sky
History of radio astronomy, Steve Torchinsky Goutelas, 4 June 2007 9
The first radio map of the sky
• Grote Reber
History of radio astronomy, Steve Torchinsky Goutelas, 4 June 2007 10
Neutral Hydrogen• 1945
– van de Hulst suggests spin-flip transition of neutral hydrogen
– first time line emission is proposed as a possibility in radio astronomy
– expected to be weak, but van de Hulst expects the abundance of HI to be very high (primordial material)
History of radio astronomy, Steve Torchinsky Goutelas, 4 June 2007 11
RADAR Astronomy
• 1947– Hey and Stewart– bouncing RADAR of the ionised tails of
meteorites– detection of daytime meteor showers– first RADAR astronomy
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Discrete Sources
• 1946– Hey, Parsons, and Phillips– Short period irregular fluctuations– 2° angular resolution
• 1948– Bolton and Stanley– 8’’ angular resolution
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HI Detected
• 1951– Ewen and Purcell in USA
• HI is the most abundance element in the universe
• radio astronomy really takes off
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Radio Observatoriesin the 50’s and 60’s
• Cambridge• Jodrell Bank• Westerbork• Parkes• Greenbank• Nançay• Arecibo• …
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Galactic structure
• 1950’s early 60’s– Oort– using HI
observations
History of radio astronomy, Steve Torchinsky Goutelas, 4 June 2007 16
Radio emissions from Jupiter
• 1955– Burke & Franklin– 22MHz
• 1958– Sloanaker– 3GHz
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Rotation of Mercury
Arecibo Radar echo shows the rotation rate of Mercury to be 59 days, and not 88 days
Pettengill & Dyce, 1965, Nature, 206, 1240
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The Cosmic Microwave Background
• 1965– Penzias and Wilson– Nobel Prize 1978
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Aperture Synthesis
• Martin Ryle at Cambridge• using Earth rotation to fill
the u-v plane• Nobel Prize 1974
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Discovery of Pulsars
• 1967– Jocelyn Bell
• “Little Green Men”• demonstrates it’s
extraterrestrial (not RFI)• perseveres!
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Very Long Baseline Interferometry
• 1971– Broten et al in Canada– et al in USA
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• 1974 at Arecibo• timing over the next
~20 years• confirms
gravitational wave radiation
• Hulse and Taylor Nobel Prize 1993
Pulsar – Neutron star binary
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The Cosmic Microwave Background
• 1990– COBE satellite– first measure of complete
Planck black-body spectrum for the CMB
– first measure of anisotropy– 2006 Nobel Prize: Mather
and Smoot
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First extra solar planet
• 1992 at Arecibo– Wolszczan & Frail
“A Planetary System around the Millisecond Pulsar PSR 1257+12” 1992, Nature, 355, 145
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Radio Schmidt and SKA
• 1990’s – proposal for a wide field of view high sensitivity
radio telescope– more on Wednesday!